<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		
		<script>
			let a = 1;
			let b = 4;
			console.log(a);
			console.log(b);
			
			function change(a ,b)
			{
				let tmp = a;
				a = b;
				b = tmp;
				
				alert(a);
				alert(b);
			}
			
			change(a,b);
			alert(a);
			alert(b);
			console.log(a);
			console.log(b);
		</script>
	</body>
</html>